C-H center dot center dot center dot O/N hydrogen bonding ability of rare gas inserted molecules was explored by investigating complexes of FKrCCH with series of the colloquial acceptor molecules using high level of ab-initio calculations. Structure, energetics, shifts in the C-H stretching frequencies as well as topological study of electron density provided unequivocal evidence for the formation of C-H center dot center dot center dot O/N hydrogen bonded complexes. Further, the strength of the hydrogen bonding in complexes of rare gas inserted molecule FKrCCH is found to be enhanced than the parent molecule FCCH which can be attributed to the increased acidity of the CH proton due to insertion of the Kr atom. (C) 2011 Elsevier B.V. All rights reserved.